The scrapbook begins with the inscription: ‘To my son, that you might know what sort of people we used to be.’
Photograph: IWM

A long-lost photograph album, compiled by a soldier who set off for the first world war never to return, has been reunited with his descendants ahead of the Armistice centenary.

Lt Henry Sacheverel Sanders pasted in family and military photographs, and annotated it with extracts from poems and musical scores, in the expectation he would die in battle, and so those who came after him could know about his life.

He compiled it after the deaths of his wife, Nicola, aged 32, from TB, and two of his three young children: Peter, aged one, and Lorna, aged four. The album would be passed to his sole surviving son, Michael, who was just five when his father was killed in action at Achiet-le-Petit in France in August 1918.

But Michael took it to his prep school, Fonthill in East Grinstead, West Sussex, and is believed to have lost it at some point.

Now, through detective work by a local historian who found the album last year, and the Imperial War Museum’s (IWM) digital “Lives of the First World War” project, Sanders’ grandchildren and great-grandchildren, who never knew the album existed, have been traced.

The cloth covered scrapbook begins with the handwritten note: “To my son, and her son, Michael … that you might know what sort of people we used to be”. Alongside is a quotation from Walt Whitman’s poem So Long: “Camerado, this is no book, who touches this touches a man”.

Sanders’ granddaughter, Hilary Mead, a retired teacher from Oxford, said its pages reflected her grandparent’s bohemian lifestyle, first in Ladbroke Road, London, and later in Caterham, Surrey, where regular visitors included Edwardian actress Cathleen Nesbitt and her fiance, the war poet Rupert Brooke.

Sanders had trained at the Royal Academy of Music and was an outstanding professional musician and some time actor. He and his wife were so enchanted by JM Barrie’s Peter Pan that Sanders took to calling himself “Peter”, signing the album: “Peter Sanders, 2nd Lieut. 18 Royal War. R., Ipswich at 1917”, which initially led to difficulties identifying relatives.

As a widower, and the father of a young son, Sanders could, perhaps, have sought exemption from overseas service. The indications were, however, that he wanted to fight and was prepared to die.

“It’s what we believe, that he did not expect to survive and that also he did not expect my father to survive, because he was a delicate baby,” said Mead.

Overwhelming sorrow at the loss of his wife and children, and the passing of friends one by one, is reflected in the quotations, and may have motivated him to sign up. “Seeing his whole world collapse, all the lovely things that had gone, I’m just guessing, but perhaps the world was a very sad place for him,” said Mead.

Ann Hacke, Fonthill school’s unofficial historian and an IWM volunteer who discovered the album among papers in storage, said: “As I was looking through it, I thought that this is someone who was writing this as a testimony with no expectation of coming back.”

Michael Sanders, who went on to become a solicitor in Norfolk, had attended Fonthill school aged 10. He later returned in the 1940s to briefly teach there, before serving in the second world war, and then taking up law as a profession. The school closed in 1985.

“He may have lost it there as a boy, or if he took it back when he was a teacher there. We will never know,” said Mead.

Michael died aged 91 in 2004, survived by his three children, including Mead, and his six grandchildren. He had inherited his parents’ musical genes, but had been able to share few memories of them as he was orphaned at such young age.

Hacke’s quest to trace descendants was initially thwarted because Sanders had used the name Peter. Using genealogy sites, she eventually discovered who the owner was, and she uploaded a photograph from the album, along with details, on the IWM site. Mead’s son, named Henry in his great-grandfather’s memory, came across Hacke’s post while researching his great-grandfather, who died aged 35. Last week the family were presented with the album at the IWM.

The album has been presented to Henry Sanders’ family. Photograph: IWM

“It is incredible. We had no idea it existed,” said Mead. She said it offered the family a much greater insight into the life of their grandparents. “The book gets to the heart of who they really were.”

Charlotte Czyzyk, project manager of the IWM’s Lives of the First World War said: “We have had some fantastic stories over the years. I think to be able to reunite a family with an artefact that is as precious as this is really very special, and makes the whole project worthwhile.”